Macrosternodesmidae

Brölemann, 1916

Macrosternodesmidae is a of flat-backed in the Polydesmida, primarily distributed in western North America with some European representatives. The family contains approximately 9 and 16 described , though taxonomic status remains disputed—some authorities treat it as a junior synonym of Trichopolydesmidae, while others recognize it as valid with two : Macrosternodesminae and Nearctodesminae. Many species are troglobionts restricted to cave systems.

Tidesmus by (c) Evrytte Carlson, some rights reserved (CC BY), uploaded by Evrytte Carlson. Used under a CC-BY license.

Macrosternodesmidae by (c) Donald Hobern, some rights reserved (CC BY). Used under a CC-BY license.

Macrosternodesmidae by (c) Derek Hennen, some rights reserved (CC BY), uploaded by Derek Hennen. Used under a CC-BY license.

Pronunciation

How to pronounce Macrosternodesmidae: //ˌmækroʊˌstɜːrnoʊˈdɛzmɪdiː//

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Identification

Macrosternodesminae: small body size (2.5–12 mm), often lacking pigment, short with bulbous , tergites with arranged on rows of . Nearctodesminae: larger body size (10–35 mm), often , orange, pink, or red, long antennae with cylindrical distal segments, tergites smooth and lacking setae. Both feature a small collum shaped like a transverse oval and well-developed paranota.

Images

Habitat

Predominantly hypogean (cave) environments, including high-altitude limestone caves; some occur in epigean settings. Western North species are associated with cave systems in Arizona, California, Colorado, and Nevada, USA, plus Baja California Norte, Mexico.

Distribution

Western North America: Arizona, California, Colorado, Nevada (USA), Baja California Norte (Mexico). Also recorded from Denmark, Norway, and Sweden (GBIF). European include Macrosternodesmus and three other genera.

Behavior

Many are troglobionts (obligate cave-dwellers), likely exhibiting troglomorphic such as reduced pigmentation and elongated appendages. Macrosternodesminae species are frequently observed in cave systems.

Ecological Role

Component of cave faunal ; contributes to in cave . In Tonto National Forest Cave #34, Arizona, the macrosternodesmid Nevadesmus superstitiona co-occurs with 31 other animal including four other troglobionts.

Similar Taxa

TrichopolydesmidaeTaxonomic synonymy disputed; some authorities treat Macrosternodesmidae as junior synonym, while others maintain both as separate with different generic compositions.
NearctodesmidaeTreated as junior synonym by some authorities; in 2017, Shear and Reddell placed Nearctodesmidae into new Nearctodesminae within Macrosternodesmidae.

More Details

Taxonomic Controversy

status disputed since 2013. Golovatch (2013) proposed Macrosternodesmidae as junior synonym of Trichopolydesmidae; Shear and Reddell (2017) rejected this, retaining Macrosternodesmidae as valid. Generic composition also contested—some authorities place Macrosternodesmus, Packardesmus, and Coloradesmus in Trichopolydesmidae instead.

Subfamily Classification

Shear and Reddell (2017) established two : Macrosternodesminae (Brölemann, 1916) with 11 including Chaetaspis, Coloradesmus, Macrosternodesmus, Nevadesmus, Ophiodesmus, Packardesmus, Pratherodesmus, Sequoiadesmus, Speodesmus, Speorthus, and Tidesmus; and Nearctodesminae (Chamberlin & Hoffman, 1950) with 5 genera including Bistolodesmus, Ergodesmus, Kepolydesmus, Leonardesmus, and Nearctodesmus.